1. Field of the Invention
The invention relates to an improved semiconductor manufacturing device in which SEL (State Excited by Light) effect can be enjoyed.
2. Prior Art
There have been known processing techniques for semiconductor devices comprising a substrate and non-monocrystalline semiconductor layer formed on the substrate. In many products according to such techniques, some undesirable effects are observed. Namely, immediately after fabrication, a highly purified semiconductor exhibits decrease of conductivity under photo annealing in atmospheric air whereas it recovers by virtue of thermal annealing. The effect appears repeatedly. The inventors have found that such a phenomenon, called Staebler-Wronski effect is observed only on semiconductors taken out from a vacuum chamber and made in contact with atmosphere.
Not only does repetition of increase and decrease in conductivity occur, but the conductivity tends to gradually decrease as with repetition of the Staebler-Wronski effect. This is undesirable especially in semiconductors applied to solar cells.